Q-139: I enjoyed reading your review of the Hobby Lobby Bonnie-20 ARF electric aircraft in the AMA’s on-line magazine, Sport Aviator. I also noted your adaptation of a set of floats for the Bonnie, permitting it to fly off of water. However, I didn’t like the use of the “golf-club” type water rudder as you pictured in your article. Are there alternatives to this approach?
A-139: I have to agree with you, I did find that the “golf-club” rudder that protrudes off the bottom of the Bonnie’s rudder does get in the way. It also makes for more complications when switching from floats to landing gears for land-based operation (because the “golf club” must be removed each time the floats are removed).
By accident I found an old water-rudder assembly (in my own shop!) that was made by the Ernst Manufacturing Co. It is fabricated from molded plastic parts and provides for easy mounting to the rear of one of your two floats (you don’t need a separate rudder on each float!). The other feature is that the rudder is held in place by rubber bands which allow the rudder to flex upward when you run the aircraft up on the shore or beach. This prevents landing loads from being transmitted up the control rod into the rudder servo.
I knew the Ernst water rudder was a perfect application, but were they still in
production? Thanks to our wonderful Internet, I was able to search and locate a
supply of these water rudders. To my surprise, Tower Hobbies still sells them as
their catalog No. LXE981 for only $6.69 (/www2.towerhobbies.com/cgi-bin/wti0093p?&C=QDE).
There is now a sidebar to my original Bonnie on Floats article that
covers the actual installation of the Ernst Water Rudder assembly to the Hobby
Lobby Floats. Look it up it is really a neat way to go!